Latch mechanism



Feb' 6, 1951 c. B. GRAHAM ETAL 2,540,941

LATCH MECHANISM Filed March 17, 1945 /M d M Patented Feb. 6, 1951 LATCHMECHANISM Clifton B. Graham and Vinton D. Carver, Oak Ridge, Tenn..assignors, by mesne assignments, to the United States of America asrepresented by the United States Atomic sion Energy Commis- ApplicationMarch 17, 1945, Serial No. 583,278

5 Claims. l

This invention relates to improvements in automatic latches or triggermechanisms and is particularly concerned with a latch or triggermechanism which is automatically operated and which can be made verysensitive to conditions to which it is responsive.

The primary object of the invention is to provide an automatic latch ortrigger mechanism which is sensitive but which is very simple in designand construction and which has no unwieldy or cumbersome parts which areapt to bind or become inoperative as a result of wear or maltreatment.

An object of the invention is to provide an automatic latch or triggermechanism comprising a spring latch member controlled by a detent, thedetent being supported by a resilient tie member, and the tie memberbeing arranged to oppose or restrain the latch spring while beingreadily movable at the point where it carries the detent so as topromote ease of actuation of the detent by automatic mechanism.

Another object of the invention is to provide an automatic latch ortrigger mechanism comprising a. spring latch member and restrainingmeans therefore comprising a detent carried on the end of a resilienttie member arranged to restrain the mechanism in latched position.

Another object of the invention is to provide a latch or triggermechanism comprising a latch member having a notch therein engageable bya. detent carried on the end of a resilient bracket or tie member.

Various other objects of my invention and numerous of its advantageswill become apparent Lfrom the following detailed description andannexed drawing wherein Figure l is a cross sectional view of a fluiddispensing nozzle having the device of my invention incorporatedtherein.

Fig. 2 is a sectional view taken along line 2-2 of Fig. 1.

Fig. 3 is a view taken along line 3--3 of Fig. 1.

The fo lowing detailed description describes an automatic liquiddispensing nozzle of the type which has an automatic shut-o5 mechanismfor shutting 01T the flow through the nozzle when the container intowhich the liquid is being dispensed fills up, and the improved latchmechanism oi our invention is described in association with theautomatic shut-olf mechanism of the nozzle. The device of our inventionnds particular application in connection with a dispensing nozzle, asdescribed, although it is understood that it may be utilized in manyother ways and in many other devices. The dispensing nozzle is described`2 in connection with the dispensing of liquid nitrogen into liquidnitrogen traps as an example of one use of the nozzle.

Referring to Fig. l, numeral I designates the liquid nitrogen dispensingvalve, the vvalve having a stem 2 extending upwardly into the housing 3within which is the manual and automatic mechanism for operating thedispensing valve. The valve I is of conventional construction, the inletbeing at the right and the outlet at the left and the port beingdesignated 35. The valve member 36 seats upwardly and is urged inseating direction by a coil spring 31 which surrounds a guide stem 38which extends downwardly from the valve member into a guide bearing 39in the lower part of the valve casing. As shown, the housing 3 isseparate from the valve body, being connected thereto by a tube 4 withthe valve stem sealed by a corrugated expansible bellows 5. The stem 2may be depressed to open the valve I by means of a handle 6 which has alug I which forms a fulcrum at the top of frame 3 and to which is linkeda latch member 8 which has a notch 9 in its center portion adapted toengage a roller on a rod I0 or pin forming a detent. Surrounding themember 8 is a coil spring II which bears against a disc I2 held in placeby a. cotter pin I3.

The operation of the parts as so far described is that when -it isdesired to open the valve I, handle 6 is merely depressed and thiscauses the handle to turn about its pivot, that is, iulcrum l, the stem2 being thus depressed to move valve I in opening direction againstbiasing spring 3l which normally urges it in closing direction. Whenhandle B is released spring 31 seals valve member 36.

The outlet of the valve I is connected to a Venturi tube I5having arestricted throat, the venturi being connected to the dispensing nozzleI6 and the nozzle carrying a shield I4 for protection against splashing.

The mechanism for automatically closing the valve I when the trap isfilled with liquid nitrogen includes a corrugat d expansible bellows I lwithin the housing 3, th movable end of the bellows I'I carrying a yokemember I8 which engages the pin or rod Iii so as to be operatable topull it out of the notch 9 when the bellows collapse. The pin or rod I0extends transversely through the arms of yoke I8 and the roller on pinI0 is between the yoke arms so as to reduce friction in movement intoand out of notch 9. (See Figs. 2 and 3.)

'I'he ends of rod I0 are engaged on the ends of spring brackets I9extending upwardly from the bottom of housing 3, the ends of thebrackets being narrowed, as may be seen on Fig. 3, and they are curledover, that is, around the ends of rod III outside of the yoke I8. Pin I9has a head at one end and a cotter pin at the other end to hold it inplace. Adjacent each bracket I9 is a slightly shorter leaf spring andthe spring brackets and leaf springs are supported from a right anglebracket 49 attached to the bottom of casing .3 by screws II, the springbrackets and leaf springs being attached to bracket 49 by screws I2;Numeral 2| designates adjusting screws extending transversely throughbracket 40 with their ends bearing against spring brackets I9. Theposition of screws 2| may be set by lock nuts as shown at 44. Thepurpose of adjusting screws 2|v is to adjust thevforce required to movethe upper ends ofsprlng brackets I9 and pin III to the left, that is outof notch 9. When screws 2| are screwed against members I9 and 20 theforce tends to bend or spring these members to the right (Figs. 1 and2). Thus a greater force is required to move the upper ends of membersI9 to the left. Screws 2| are suitably adjusted and in this way theiorce required to pull pin III out of notch 9 is adjusted. Springbrackets I9 'form resilient tie members which; through the detentformedV by pin I0, restrain upward movement of member 8 when pin III isengaged' in notch 9 in member 8.

The interior of the bellows I1 is connected by tube 23 to a plug member24 having an internal recess which communicates through an oriiicemember 25 and a channel 28 with the restricted throat of the venturi.The recess within plug member24 also communicates by means of a tube 21with a vertical tube 28 extending downwardly within the vertical portionof the nozzle I6. At the upper end of tube 29 is a valve member 29carried on the end of a rod 30 mounted longitudinally 'within the tube28. The tube 28 and the rod are made of materials having differentcoeflicients of expansion so that the valve 29 is normally away from itsseat to vent the tubes, but when the expanding nitrogen cornes incontact with the tube 28 and rod 30, contraction of the different metalscause valve member 29 to seat, thus closing the vent. The purpose of thestructure just" described will become apparent below. l

In operation, when it is desired to ll a liquid 9 unlatching the latchmechanism, and when this happens, the valve I automatically closes.'I'hat is, the spring which is part of valve I moves the stem 2upwardly, moving fulcrum 1 bodily upwardly and pulling member 8 upwardlyagainst the force of spring II. If the handle 6 is now released by theoperator, the spring II will return the latch mechanism, and the fulcrum1 back into the positions shown on Fig. 1 with the rod III reiatchinginto the notch 9 as soon as bellows I1 expands.

The purpose of the valve member 29 and the vent in the tube 28 is toprevent the automatic mechanism operating to close the valve in responseto the initial now of vaporized liquid nitrogen which passes through thevalve I when it is first opened. If the tube connections were not ventedby valve member 29 when valve I is rst opened, this initial ilow ofvaporized liquid nitrogen might. produce such a vacuum in venturi I5 asto operate the bellows mechanism causing nitrogen trap with liquidnitrogen, the nozzle I6 is inserted into the trap and then the valve Iisopened by depressing handle 6 in the manner described above. As thelevel of liquid nitrogen in the liquid trap rises, it immerses the lowerend of the nozzle I 6 covering a small orifice 3| which communicateswith the interior of tube 28. When this happens, the valve willautomatically close in a manner to be described. When liquid nitrogen isflowing through the valve I and through venturi I5 a reduced pressure isproduced in its restricted throat which tends to reduce the pressure inplug member 24 and also within the bellows -I1 which communicates by wayof tube 23. l

When orice '3| is above the level of liquid nitrogen, however, there isvery little evacuation, that is, reduction of pressure, and bellows 'I1does not function. However, when orice 3| becomes covered, the pressurewithin the bellows I1 is reduced in the manner described and it tends tocollapse, moving yoke member I8 and rod I0' to the left so that the rodis pulled out of notch it to close the valve. By the time that theinitial ow of vaporized liquid nitrogen has passed, valve member 29 willhave seated sealing the vent and thus preparing the system toautomatically operate when the trap becomes illled with liqui nitrogen.

From the foregoing those skilled in the art will observe that we haveprovided an eilcient and sensitive latch mechanism characterized bysimplicity of design and fabrication and possessing improved operatingqualities.

`The foregoing disclosure is representative of the preferred form of ourinvention and it is intended that it be interpreted in an illustrativerather than a limiting sense, and that the scope of the invention bedetermined only in accordance withthe claims appendedhereto.

We claim:

l. An automatic latch mechanism, comprising in combination, a. latchmember having latched and unlatched positions and having a portionadapted to be engaged by a detent, means urging said member towardunlatched position, re-

.` straining means comprising an element adapted to engage said portionand a bendable tensile member iixed at one end and attached at its freeend to said element, said tensile member having a bending moment tendingto hold said element in engagement with said portion, whereby saidtensile member develops a tensile stress opposing said urging means andrestraining said latch member in its latched position, and meansoperable to move said element against said bending moment out ofengagement with said portion to release said urging means.

2. An automatic latch mechanism comprising in combination, a latchmember having latched and unlatched positions and having a notchtherein, means urging said member toward unlatched position, restrainingmeans comprising a roller detent engageable in said notch, a bendabletensile member xed at one end and attached at its free end to saiddetent. and means bearing against said tensile member intermediate itsends to apply a bending moment to said tensile member tending to holdsaid detent in engagement with said notch, whereby said tensile memberdevelops a tensile stress opposing said urging means and restrainingsaid latch member in its latohed position, and means operable to movesaid detent and unlatched positions and having a portion adapted to beengaged by a detent, means urging said member toward unlatched position,restraining means comprising an element adapted to engage said portionand a bendable tensile member xed at one end and attached at'its freeend to said element, said tensile member having a bending moment tendingto hold said element in engagement with said portion, whereby saidtensile member develops a tensile stress opposing said urging means andrestraining said latch member in its latched position, means operable tomove said element against said bending moment out of engagement withsaid portion to release said urging means, and means for adjusting thebending moment of said tensile member.

4. Apparatus, as claimed in claim 1, wherein said tensile member ispositioned to extend generally parallel to the direction along whichsaid latch member is urged by said urging means.

5. An automatic latch mechanism, comprising in combination, a latchmember having latched and unlatched positions and having a portionadapted to be engaged by a detent, means urging said member towardunlatched position, restraining means comprising an element adapted toengage said portion, a bendable tensile member fixed at one end andattached at its free end at spaced positions to said element, andmanually adjustable means bearing against said tensile memberintermediate its ends to apply a bending moment to said tensile membertending to hold said element in engagement with said portion, wherebysaid tensile member develops a tensile stress opposing said urging meansand restraining said latch member in its latohed position, and meansoperable to move said element against said bending moment out Vofengagement with said portion to release said urging means. CLIFTON B.GRAHAM. VINTON D. CARVER.

REFERENGES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS

